Genome-wide identification of the CNGC gene family and negative regulation of drought tolerance by HvCNGC3 and HvCNGC16 in transgenic Arabidopsis thaliana.

Cyclic nucleotide-gated ion channels (CNGCs), as non-selective cation channels, play essential roles in plant growth and stress responses. However, they have not been identified in Qingke (Hordeum vulgare L.). Here, we performed a comprehensive genome-wide identification and function analysis of the HvCNGC gene family to determine its role in drought tolerance. Phylogenetic analysis showed that 27 HvCNGC genes were divided into four groups and unevenly located on seven chromosomes. Transcription analysis revealed that two closely related members of HvCNGC3 and HvCNGC16 were highly induced and the expression of both genes were distinctly different in two extremely drought-tolerant materials. Transient expression revealed that the HvCNGC3 and HvCNGC16 proteins both localized to the plasma membrane and karyotheca. Overexpression of HvCNGC3 and HvCNGC16 in Arabidopsis thaliana led to impaired seed germination and seedling drought tolerance, which was accompanied by higher hydrogen peroxide (H2O2), malondialdehyde (MDA), proline accumulation and increased cell damage. In addition, HvCNGC3 and HvCNGC16-overexpression lines reduced ABA sensitivity, as well as lower expression levels of some ABA biosynthesis and stress-related gene in transgenic lines. Furthermore, Yeast two hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays revealed that HvCNGC3 and HvCNGC16 interacted with calmodulin/calmodulin-like proteins (CaM/CML), which, as calcium sensors, participate in the perception and decoding of intracellular calcium signaling. Thus, this study provides information on the CNGC gene family and provides insight into the function and potential regulatory mechanism of HvCNGC3 and HvCNGC16 in drought tolerance in Qingke.

Bioinformatics, expression analysis, and functional verification of allene oxide synthase gene HvnAOS1 and HvnAOS2 in qingke.

Allene oxide synthase (AOS) is a key enzyme involved in the jasmonic acid (JA) synthesis pathway in plants. To explore its function on the regulatory mechanism of JA synthesis, we screened and identified two AOS genes HvnAOS1 and HvnAOS2 in qingke. Both HvnAOS1 and HvnAOS2 contained conserved heme-binding motif, which is most closely related to AtsAOS2, indicating controlled dehydration of fatty acid hydroperoxides to allene oxides. Molecular docking simulations identified the key amino acid sites that were important for heme binding and interaction with 13(S)-HPOT, respectively. The expression pattern also indicated that HvnAOS1 and HvnAOS2 were highly induced by JA, abscisic acid, and salicylic acid. Subcellular localization of HvnAOS1 and HvnAOS2 using transient expression of Agrobacterium tumefaciens showed the green fluorescent protein signal in the cell cytoplasm of the N. benthamiana leaves. Overexpression of HvnAOS1 and HvnAOS2 in Arabidopsis aos mutant restored male fertility and plant resistance to Botrytis cinerea, indicating that HvnAOS1 and HvnAOS2 can restore the functions of AOS in Arabidopsis aos mutant.

Comparative transcriptome analysis of major lodging resistant factors in hulless barley.

Hulless barley (Hordeum vulgare L. var. nudum Hook. f.), belonging to the genus Gramineae, has high and steady output and thus considered as a principal food crop by Tibetan people. Hulless barley grain can be used for food, brewing, and functional health product development, while its straw serves as an essential supplementary forage and is a crucial cereal crop. Lodging can reduce the yield and quality of barley grain and straw, and it hinders mechanical harvesting. It is a significant factor affecting high and stable yields of barley. Unlike other Poaceae plants (such as rice, wheat), hulless barley is mainly grown in high-altitude regions, where it is susceptible to low temperatures, strong winds, and heavy rainfall. As a result, its stem lodging resistance is relatively weak, making it prone to lodging during the growth period. In this study, we observed that the lignin concentration and the contents of lignin monomers (H, S, and G), and neutral detergent fibre of the lodging-resistant variety Kunlun14 were substantially greater than those of the lodging-sensitive variety Menyuanlianglan. We performed the weighted gene co-expression network analysis (WGCNA) and Short Time-series Expression Miner (STEM) analysis of both the lodging-resistant and lodging-sensitive varieties. Through transcriptome sequencing analysis at different developmental stages, combined with the previously annotated genes related to lodging resistance, a total of 72 DEGs were identified. Among these DEGs, 17 genes were related to lignin, cellulose, and hemicellulose synthesis or regulation, including five transcription factors about NAC, MYB and WRKY. Our results provide a basis for further exploring the molecular mechanism of stem lodging resistance in hulless barley and provide valuable gene resources for stem lodging resistance molecular breeding.

Cloning, subcellular localization and expression of phosphate transporter gene HvPT6 of hulless barley.

Deficiency of phosphate (Pi) is one of the main growth-limiting factors for crops. Generally, phosphate transporters play a key role in the uptake of P in the crops. However, current knowledge regarding the molecular mechanism underlying Pi transport is still limited. In this study, a phosphate transporter (PT) gene, designated HvPT6, was isolated from a cDNA library constructed from hulless barley "Kunlun 14." The promoter of HvPT6 showed a large number of elements related to plant hormones. The expression pattern also indicated that HvPT6 was highly induced by low phosphorus, drought, abscisic acid, methyl jasmonate and gibberellin. Phylogenetic tree analysis revealed that HvPT6 belongs to the same subfamily of the major facilitator superfamily as OsPT6 from Oryza sativa. Subcellular localization of HvPT6:GFP using transient expression of Agrobacterium tumefaciens showed the green fluorescent protein signal in the membrane and nucleus of the Nicotiana benthamiana leaves. Overexpressing HvPT6 led to a longer and higher lateral root length and dry matter yield in the transgenic Arabidopsis lines under low Pi conditions, indicating that HvPT6 improves plant tolerance under Pi-deficient conditions. This study will lay a molecular basis for phosphate absorption mechanism in barley and breeding barley with high-efficient phosphate uptake.

Genome-wide identification of WD40 transcription factors and their regulation of the MYB-bHLH-WD40 (MBW) complex related to anthocyanin synthesis in Qingke (Hordeum vulgare L. var. nudum Hook. f.).

BACKGROUND: WD40 transcription factors, a large gene family in eukaryotes, are involved in a variety of growth regulation and development pathways. WD40 plays an important role in the formation of MYB-bHLH-WD (MBW) complexes associated with anthocyanin synthesis, but studies of Qingke barley are lacking. RESULTS: In this study, 164 barley HvWD40 genes were identified in the barley genome and were analyzed to determine their relevant bioinformatics. The 164 HvWD40 were classified into 11 clusters and 14 subfamilies based on their structural and phylogenetic protein profiles. Co-lineage analysis revealed that there were 43 pairs between barley and rice, and 56 pairs between barley and maize. Gene ontology (GO) enrichment analysis revealed that the molecular function, biological process, and cell composition were enriched. The Kyoto Encyclopedia of Genes and Genomes (KEGG) results showed that the RNA transport pathway was mainly enriched. Based on the identification and analysis of the barley WD40 family and the transcriptome sequencing (RNA-seq) results, we found that HvWD40-140 (WD40 family; Gene ID: r1G058730), HvANT1 (MYB family; Gene ID: HORVU7Hr1G034630), and HvANT2 (bHLH family; Gene ID: HORVU2Hr1G096810) were important components of the MBW complex related to anthocyanin biosynthesis in Qingke, which was verified via quantitative real-time fluorescence polymerase chain reaction (qRT-PCR), subcellular location, yeast two-hybrid (Y2H), and bimolecular fluorescent complimentary (BiFC) and dual-luciferase assay analyses. CONCLUSIONS: In this study, we identified 164 HvWD40 genes in barley and found that HvnANT1, HvnANT2, and HvWD40-140 can form an MBW complex and regulate the transcriptional activation of the anthocyanin synthesis related structural gene HvDFR. The results of this study provide a theoretical basis for further study of the mechanism of HvWD40-140 in the MBW complex related to anthocyanin synthesis in Qingke.

Wide-Range Portrayal of AP2/ERF Transcription Factor Family in Maize (Zea mays L.) Development and Stress Responses.

The APETALA2/Ethylene-Responsive Transcriptional Factors containing conservative AP2/ERF domains constituted a plant-specific transcription factor (TF) superfamily, called AP2/ERF. The configuration of the AP2/ERF superfamily in maize has remained unresolved. In this study, we identified the 229 AP2/ERF genes in the latest (B73 RefGen_v5) maize reference genome. Phylogenetic classification of the ZmAP2/ERF family members categorized it into five clades, including 27 AP2 (APETALA2), 5 RAV (Related to ABI3/VP), 89 DREB (dehydration responsive element binding), 105 ERF (ethylene responsive factors), and a soloist. The duplication events of the paralogous genes occurred from 1.724-25.855 MYA, a key route to maize evolution. Structural analysis reveals that they have more introns and few exons. The results showed that 32 ZmAP2/ERFs regulate biotic stresses, and 24 ZmAP2/ERFs are involved in responses towards abiotic stresses. Additionally, the expression analysis showed that DREB family members are involved in plant sex determination. The real-time quantitative expression profiling of ZmAP2/ERFs in the leaves of the maize inbred line B73 under ABA, JA, salt, drought, heat, and wounding stress revealed their specific expression patterns. Conclusively, this study unveiled the evolutionary pathway of ZmAP2/ERFs and its essential role in stress and developmental processes. The generated information will be useful for stress resilience maize breeding programs.

Influence of configuration and anchor in ligamentous augmentation to prevent proximal junctional kyphosis: A finite element study.

Ligament augmentation has been applied during spinal surgery to prevent proximal junctional kyphosis (PJK), but the configuration and distal anchor strategies are diverse and inconsistent. The biomechanics of different ligament augmentation strategies are, therefore, unclear. We aimed to create a finite element model of the spine for segments T6-S1. Model Intact was the native form, and Model IF was instrumented with a pedicle screw from segments T10 to S1. The remaining models were based on Model IF, with ligament augmentation configurations as common (CM), chained (CH), common and chained (CHM); and distal anchors to the spinous process (SP), crosslink (CL), and pedicle screw (PS), creating SP-CH, PS-CHM, PS-CH, PS-CM, CL-CHM, CL-CH, and CL-CM models. The range of motion (ROM) and maximum stress on the intervertebral disc (IVD), PS, and interspinous and supraspinous ligaments (ISL/SSL) was measured. In the PS-CH model, the ROM for segments T9-T10 was 73% (of Model Intact). In the CL-CHM, CL-CH, CL-CM, PS-CM, and PS-CHM models, the ROM was 8%, 17%, 7%, 13%, and 30%, respectively. The PS-CH method had the highest maximum stress on IVD and ISL/SSL, at 80% and 72%, respectively. The crosslink was more preferable as the distal anchor. In the uppermost instrumented vertebrae (UIV) + 1/UIV segment, the CM was the most effective configuration. The PS-CH model had the highest flexion load on the UIV + 1/UIV segment and the CL-CM model provided the greatest reduction. The CL-CM model should be verified in a clinical trial. The influence of configuration and anchor in ligament augmentation is important for the choice of surgical strategy and improvement of technique.

Accumulation and regulation of anthocyanins in white and purple Tibetan Hulless Barley (Hordeum vulgare L. var. nudum Hook. f.) revealed by combined de novo transcriptomics and metabolomics.

BACKGROUND: Colored barley, which may have associated human health benefits, is more desirable than the standard white variety, but the metabolites and molecular mechanisms underlying seedcoat coloration remain unclear. RESULTS: Here, the development of Tibetan hulless barley was monitored, and 18 biological samples at 3 seedcoat color developmental stages were analyzed by transcriptomic and metabolic assays in Nierumuzha (purple) and Kunlun10 (white). A total of 41 anthocyanin compounds and 4186 DEGs were identified. Then we constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley, including 19 genes encoding structural enzymes in 12 classes (PAL, C4H, 4CL, CHS, CHI, F3H, F3'H, DFR, ANS, ANR, GT, and ACT). 11 DEGs other than ANR were significantly upregulated in Nierumuzha as compared to Kunlun10, leading to high levels of 15 anthocyanin compounds in this variety (more than 25 times greater than the contents in Kunlun10). ANR was significantly upregulated in Kunlun10 as compared to Nierumuzha, resulting in higher contents of three anthocyanins compounds (more than 5 times greater than the contents in Nierumuzha). In addition, 22 TFs, including MYBs, bHLHs, NACs, bZips, and WD40s, were significantly positively or negatively correlated with the expression patterns of the structural genes. Moreover, comparisons of homologous gene sequences between the two varieties identified 61 putative SNPs in 13 of 19 structural genes. A nonsense mutation was identified in the coding sequence of the ANS gene in Kunlun10. This mutation might encode a nonfunctional protein, further reducing anthocyanin accumulation in Kunlun10. Then we identified 3 modules were highly specific to the Nierumuzha (purple) using WGCNA. Moreover, 12 DEGs appeared both in the putative proanthocyanin-anthocyanin biosynthesis pathway and the protein co-expression network were obtained and verified. CONCLUSION: Our study constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley. A series of compounds, structural genes and TFs responsible for the differences between purple and white hulless barley were obtained in this pathway. Our study improves the understanding of the molecular mechanisms of anthocyanin accumulation and biosynthesis in barley seeds. It provides new targets for the genetic improvement of anthocyanin content and a framework for improving the nutritional quality of barley.

Genome-Wide Association Mapping of Hulless Barely Phenotypes in Drought Environment.

Drought stress is one of the main factors restricting hulless barley (Hordeum vulgare L. var. nudum Hook. f.) yield. Genome-wide association study was performed using 269 lines of hulless barley to identify single-nucleotide polymorphism (SNP) markers associated with drought-resistance traits. The plants were cultured under either normal or drought conditions, and various quantitative traits including shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, leaf fresh weight, leaf saturated fresh weight, leaf dry weight, ratio of root and shoot fresh weight, ratio of root and shoot dry weight, shoot water loss rate, root water loss rate, leaf water content and leaf relative water content, and field phenotypes including main spike length, grain number per plant, grain weight per plant, thousand grain weight (TGW), main spike number, plant height, and effective spike number of plants were collected. After genotyping the plants, a total of 8,936,130 highly consistent population SNP markers were obtained with integrity > 0.5 and minor allele frequency > 0.05. Eight candidate genes potentially contributed to the hulless barley drought resistance were obtained at loci near significant SNPs. For example, EMB506, DCR, and APD2 genes for effective spike number of plants, ABCG11 gene for main spike number (MEN), CLPR2 gene for main spike length, YIP4B gene for root and shoot dry weight (RSWD), and GLYK and BTS genes for TGW. The SNPs and candidate genes identified in this study will be useful in hulless barley breeding under drought resistance.

Impacts of Continuous Cropping on Fungal Communities in the Rhizosphere Soil of Tibetan Barley.

Microbial community structures and keystone species play critical roles in soil ecological processes; however, their responses to the continuous cropping of plants are virtually unknown. Here, we investigated the community dynamics and keystone species of fungal communities in the rhizosphere soils of continuously cropped Tibetan barley (a principal cereal cultivated on the Qinghai-Tibetan Plateau). We found that the Chao1 and Phylogenetic Diversity (PD) indices decreased with increased cropping years. The relative abundance of the genera Cystofilobasidium, Mucor, and Ustilago increased with the extension of continuous cropping years, whereas Fusarium showed the opposite pattern. Furthermore, long-term monocropped Tibetan barley simplified the complexity of the co-occurrence networks. Keystone operational taxonomic units (OTUs) changed with continuous cropping, and most of the keystone OTUs belonged to the phylum Ascomycota, suggesting their important roles in rhizosphere soil. Overall, this study revealed that the continuous cropping of Tibetan barley impacted both on the richness, phylogenetic diversity, and co-occurrence network of fungal community in the rhizosphere. These findings enhance our understanding of how rhizosphere fungal communities respond to monocropped Tibetan barley.

The complete chloroplast genome sequence of Hordeum distichon (Poales: Poaceae).

Hordeum distichon (H. distichon) is a two-row cultivated barley used as food and as a feed crop. Chloroplast genome is an excellent way to study the genetic structure and evolutionary process of natural population of plant species in recent years. In this study, the complete chloroplast genome of H. distichon was sequenced and analyzed: the size of the chloroplast genome is 136,462 bp in length, including a large single copy region (LSC) of 80,597 bp, a small single copy region (SSC) of 12,701 bp, and a pair of inverted repeated regions (IR) of 21,582 bp; the H. distichon chloroplast genome encodes 129 genes, including 83 protein-coding genes, 38 tRNA genes, and eight rRNA genes; the overall GC-content of the chloroplast genome was 38.32%, with the LSC, SSC, and IR regions being 36.31%, 32.33%, and 43.83%, respectively. Phylogenetic analysis based on 32 species with the maximum likelihood (ML) method indicated that H. distichon was closely related to Hordeum vulgare.

Genome wide association study of plant height and tiller number in hulless barley.

Hulless barley (Hordeum vulgare L. var. nudum), also called naked barley, is a unique variety of cultivated barley. The genome-wide specific length amplified fragment sequencing (SLAF-seq) method is a rapid deep sequencing technology that is used for the selection and identification of genetic loci or markers. In this study, we collected 300 hulless barley accessions and used the SLAF-seq method to identify candidate genes involved in plant height (PH) and tiller number (TN). We obtained a total of 1407 M paired-end reads, and 228,227 SLAF tags were developed. After filtering using an integrity threshold of >0.8 and a minor allele frequency of >0.05, 14,504,892 single-nucleotide polymorphisms (SNP) loci were screened out. The remaining SNPs were used for the construction of a neighbour-joining phylogenetic tree, and the three subcluster members showed no obvious differentiation among regional varieties. We used a genome wide association study approach to identify 1006 and 113 SNPs associated with TN and PH, respectively. Based on best linear unbiased predictors (BLUP), 41 and 29 SNPs associated with TN and PH, respectively. Thus, several of genes, including Hd3a and CKX5, may be useful candidates for the future genetic breeding of hulless barley. Taken together, our results provide insight into the molecular mechanisms controlling barley architecture, which is important for breeding and yield.

LncRNA ANRIL promotes multiple myeloma progression and bortezomib resistance by EZH2-mediated epigenetically silencing of PTEN.

Multiple myeloma (MM) is a plasma cell malignancy of bone marrow. In the present study, we aimed to study the function and potential mechanism of the antisense non-coding RNA in the INK4 Locus (ANRIL) in MM. The expression levels of ANRIL in MM patients and healthy donors were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The effects and mechanisms of ANRIL in MM were evaluated by cell viability assay, BrdU incorporation assay, tumor xenograft model, flow cytometry, western blot, RNA immunoprecipitation (RIP), transcriptome RNA sequencing, and chromatin immunoprecipitation (ChIP). We found that ANRIL was upregulated in MM patients and cell lines, and associated with advanced international staging system (ISS) stage and poor overall survival. Enforced ANRIL expression promoted proliferation and tumor xenograft growth of MM cells, while knockdown of ANRIL exhibited opposite effects. Moreover, ANRIL overexpression increased the half-maximal inhibitory concentration (IC50) of bortezomib and reduced bortezomib-induced apoptosis in MM cells. ANRIL was found to accumulate in the nuclei of MM cells, and interact with EZH2 by RIP assay. Transcriptome RNA sequencing identified PTEN as a target of ANRIL in MM cells. In the ChIP assay, knockdown of ANRIL reduced EZH2 occupancy and H3K27me3 binding to the promoter region of PTEN. Furthermore, EZH2 knockout or PTEN restoration abrogated the effects caused by ANRIL overexpression in MM cells. Our results indicated that ANRIL exerted oncogenic functions and conferred chemoresistance of MM cells by EZH2-mediated epigenetically silencing of PTEN.

Rhizosphere Bacterial Community Response to Continuous Cropping of Tibetan Barley.

Long-term continuous cropping influences the nutrient of soil and microbiome of the rhizosphere, resulting in the yield decrease of crops. Tibetan barley is a dominant cereal crop cultivated at high altitudes in Tibet. Its growth and yield are negatively affected by continuous cropping; however, the response of the rhizosphere microbial community to continuous cropping remains poorly understood. To address this question, we investigated the bacterial community structure and conducted predictive functional profiling on rhizosphere soil from Tibetan barley monocropped for 2-6 years. The results revealed that long-term continuous cropping markedly decreased total nitrogen and available nitrogen in rhizosphere soil. Illumina high-throughput sequencing of 16S rRNA genes indicated that the bacterial community was altered by continuous cropping; operational taxonomic units (OTUs), Shannon index, and Faith Phylogenetic Diversity decreased with increasing monocropping duration. Relative abundances of family Pseudomonadaceae, Cytophagaceae, and Nocardioidaceae were significantly increased, while those of Chitinophagaceae and Sphingomonadaceae were significantly decreased (all p < 0.05). Besides, continuous cropping significantly increased the abundance of bacteria associated with chemoheterotrophy, aromatic compound degradation, and nitrate reduction (p < 0.05). Generalized boosted regression model analysis indicated that total nitrogen was the most important contributor to the bacterial community diversity, indicating their roles in shaping the rhizosphere bacterial community during continuous cropping. Overall, continuous cropping had a significant impact on the structure of bacterial communities in rhizosphere soil of Tibetan barley, and these results will improve our understanding of soil bacterial community regulation and soil health maintenance in Tibetan barley farm systems.

Lumbar decompression and lumbar interbody fusion in the treatment of lumbar spinal stenosis: A systematic review and meta-analysis.

BACKGROUND: The goal of this study was to review relevant randomized controlled trials in order to determine the efficacy of decompression and lumbar interbody fusion in the treatment of lumbar spinal stenosis. METHOD: Using appropriate keywords, we identified relevant studies in PubMed, the Cochrane library, and Embase. Key pertinent sources in the literature were also reviewed, and all articles published through July 2019 were considered for inclusion. For each study, we assessed odds ratios, mean difference, and 95% confidence interval to assess and synthesize outcomes. RESULT: Twenty-one randomized controlled trials were eligible for this meta-analysis with a total of 3636 patients. Compared with decompression, decompression and fusion significantly increased length of hospital stay, operative time and estimated blood loss. Compared with fusion, decompression significantly decreased operative time, estimated blood loss and overall visual analogue scale (VAS) scores. Compared with endoscopic decompression, microscopic decompression significantly increased length of hospital stay, and operative time. Compared with traditional surgery, endoscopic discectomy significantly decreased length of hospital stay, operative time, estimated blood loss, and overall VAS scores and increased Japanese Orthopeadic Association score. Compared with TLIF, MIS-TLIF significantly decreased length of hospital stay, and increased operative time and SF-36 physical component summary score. Compared with multi-level decompression and single level fusion, multi-level decompression and multi-level fusion significantly increased operative time, estimated blood loss and SF-36 mental component summary score and decreased Oswestry disability index score. Compared with decompression, decompression with interlaminar stabilization significantly decreased operative time and the score of Zurich claudication questionnaire symptom severity, and increased VAS score. CONCLUSION: Considering the limited number of included studies, we still need larger-sample, high-quality, long-term studies to explore the optimal therapy for lumbar spinal stenosis.

Postoperative shed autologous blood reinfusion does not decrease the need for allogeneic blood transfusion in unilateral and bilateral total knee arthroplasty.

Postoperative shed autologous blood reinfusion techniques have been used for decades in total knee arthroplasty (TKA), but the effectiveness of this procedure is still a matter of debate. This multicenter retrospective study investigated the medical records of patients who underwent unilateral and bilateral TKA from January 1, 2015 to December 31, 2017 in three hospitals. According to whether postoperative shed autologous blood reinfusion was used, the patients were divided into the control group and the shed autologous blood reinfusion group. The volume of perioperative infusion of red blood cells and plasma, the blood transfusion-related costs, and the postoperative hospital stay were compared between the two groups of patients. A total of 200 unilateral and 74 bilateral TKA were included after successful matching. Among the patients who underwent unilateral TKA, the control group and the shed autologous blood reinfusion group had 95 and 91 patients, respectively, who received allogeneic blood infusion (P = 0.268). There was no significant difference in the number of units of allogeneic red blood cells infused (P = 0.154), while the transfusion-related cost was increased (P<0.001). The same phenomena were observed over the patients underwent bilateral TKA. Shed autologous blood reinfusion does not reduce the need for infusing allogeneic red blood cells. In addition, the procedure increases patient expense and may also lead to an extended postoperative hospital stay.

Stiffness of the locking compression plate as an external fixator for treating distal tibial fractures: a biomechanics study.

BACKGROUND: Locking compress plate, as external fixator, is an attractive technique for distal tibial fracture treatment. But it still remains unclear whether the external LCP has sufficient stiffness. Thus, the present study aims to make a comprehensive evaluation of the stiffness of external locking compress plate when it is used as an external fixator in distal tibial fractures treatment. METHODS: Composite tibia was used to simulate distal tibia fracture (Orthopedic Trauma Association type 43 A3 fracture). The fractures were stabilized with medial distal tibial locking compress plates (LCP group), medial distal tibial locking compress plates with 30-mm plate-bone distances (EF-tibia group), and medial distal femur locking compress plates with 30-mm plate-bone distances (EF-femur group). Stiffness of each configuration was measured under axial compression loading and in axial torsion loading directions. Compression stiffness and torsional rigidity were compared across different groups. RESULTS: Compared with LCP group, (1) EF-tibia group showed significantly lower (p < 0.001) compression stiffness and torsional rigidity; (2) EF-femur group showed significantly lower (p < 0.001) compression stiffness, but significantly higher (p < 0.001) torsional rigidity. CONCLUSIONS: The results indicated that locking compress plate as an external fixator was flexible, and the distal femur locking compress plate was preferred over the distal tibial locking compress plate to be an external fixator in distal tibia fracture treatment.